The present disclosure generally relates to connecting components constructed from dissimilar materials. More particularly, the present disclosure relates to a capacitor discharge welding operation for connecting high strength steel tubes to cast iron members using an adapter ring.
Designers and engineers of vehicles have struggled with the challenge of connecting components constructed from different materials for quite some time. This challenge arises frequently because certain components lend themselves to being constructed from certain types of materials more than others. In particular, vehicle suspension components such as steering knuckles, brake spiders and trailing arms often have relatively complex shapes that are much more easily cast than produced by other manufacturing processes. Cast iron is a typical material used due to its low cost and relatively high strength. On the other hand, more simple structural members may be formed from rolled sheet or extruded tubes. Components having planar sheet or tubular profiles may be constructed from a number of materials including low carbon steel, high strength micro-alloyed steel and aluminum. Other components may be constructed using other processes such as forging. Forged components may be constructed from yet another set of engineering materials.
Difficulties arise when attempting to structurally interconnect components made from the various materials. In particular, welding cast iron to steel typically results in a brittle weld connection due to the high carbon content of the cast iron. A brittle weld is created because the typical weld process of MIG welding forms a nugget-type or fusion weld. During MIG welding, the interface between the two components to be welded is heated to the melting point of both workpieces. After cooling and recombination of material, a nugget forms. The nugget contains all of the alloys of the two materials. Some of these combinations may have undesirable characteristics contributing to the brittle weld connection. In sum, the AC welding operation imparts too much heat to the welded components
Other processes to join dissimilar materials, specifically cast iron and steel, have been utilized. In one example, a magnetic arc system begins by engaging a face of a cast iron component with a face of a high strength steel component. Current is passed through both pieces. The workpieces are moved apart and an electric arc is formed. The electric arc is chased by a magnetic field. The ends of the components in contact with the electric arc heat up to the point of melting. The components are then pushed back together at a predetermined load to form the joint. While this method may produce desirable joints, it is very expensive due to the very high cost of the machines cooperating with one another to define the magnetic arc system. Accordingly, improvements in the field of interconnecting structural components having different materials are still desirable.